Systematic Review

By Dr. Ludovica Caterini , Dr. Martina Mezio , Dr. Martina Dari , Dr. Elisa Pacella , Dr. Denise Giovannoni
Corresponding Author Dr. Ludovica Caterini
Oral and Maxillo Facial Sciences Department, Orthognathodontics Unit, La Sapienza - Rome - Italy , - Italy
Submitting Author Dr. Ludovica Caterini
Other Authors Dr. Martina Mezio
Oral and Maxillo Facial Sciences Department, Orthognathodontics Unit, La Sapienza - Rome - Italy , - Italy

Dr. Martina Dari
Oral and Maxillo Facial Sciences Department, Orthognathodontics Unit, La Sapienza - Rome - Italy , - Italy

Dr. Elisa Pacella
Oral and Maxillo Facial Sciences Department, Orthognathodontics Unit, La Sapienza - Rome - Italy , - Italy

Dr. Denise Giovannoni
Oral and Maxillo Facial Sciences Department, Orthognathodontics Unit, La Sapienza - Rome - Italy , - Italy


dental agenesis, congenitally missing lateral incisors, associated dental anomalies, orthodontics

Caterini L, Mezio M, Dari M, Pacella E, Giovannoni D. Clinical features of maxillary lateral incisor agenesis and associated dental anomalies: a systematic review. WebmedCentral ORTHODONTICS 2017;8(10):WMC005341

This is an open-access article distributed under the terms of the Creative Commons Attribution License(CC-BY), which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
Submitted on: 20 Oct 2017 05:42:46 PM GMT
Published on: 24 Oct 2017 06:55:01 AM GMT


The maxillary lateral incisor is the second most frequently missing tooth in the dental arch.

The aim of this study was to review literature data for  maxillary lateral incisor agenesis, unilateral and bilateral, and associated dental anomalies in an orthodontic population.

Research suggests that several clinical features are commonly seen, dental anomalies commonly associated with agenesis of maxillary lateral incisors should be investigated in adults and especially in young people for early diagnosis, which is crucial for the orthodontist in order to design a proper therapeutic plan.


Tooth agenesis is one of the most common congenital anomalies occurring in the permanent dentition. The condition concerns the non-development of six or more teeth. It can occur as part of a recognised genetic syndrome or as a nonsyndromic isolated trait1.

Agenesis is the result of a disorder of the dental lamina during the training process. Should anomalies occur during the calcification and dental gems formation processes, the dental lamina may remain involved and damaged giving rise to phenomena of dental absence that can be total or partial, affecting both the dental elements of the deciduous and permanent dentition. Although local, systemic and genetic factors have been implicated in the aetiology of this anomaly, the extent to which genetic and environmental factors are involved remains unknown2,3.

The maxillary lateral incisor is the second most frequently missing tooth after the mandibular second premolar (not including third molars)4.

They represent one of the most common number anomalies in dental practice5.

It was demonstrated that higher frequencies of maxillary lateral incisors agenesis have been reported in females than in males, as with all dental agenesis6.

Furthermore Polder et al. (2004) found that bilateral agenesis of maxillary lateral incisors occurred more often than unilateral agenesis4 , and that it is often associated with dental anomalies6.

Dental anomalies such as peg-shaped incisors, taurodontism, transposed teeth, supernumerary teeth, and ectopic eruption may occur in subjects with tooth agenesis7,8. Anomalies of the eruptive path  related with agenesis of upper lateral incisors are also associated with upper canines and lower second premolars.

The aim of this study was to review literature data for  maxillary lateral incisor agenesis and associated dental anomalies in an orthodontic population.


Many works have been published on international literature about maxillary lateral incisor agenesis and associated dental anomalies. The systematic review of literature has been performed on the principal medical databases: PubMed (Medline), Embase and Scopus.

The keywords used were: dental agenesis, congenitally missing lateral incisors, associated dental anomalies.

No restrictions of time have been fixed but the search only included italian, spanish and english language.

The results have been filtered and valued following our eligibility criteria and then organized following the PRISMA method.

The search identified 15,322 abstracts, which were reviewed manually and each article of interest was marked for further review.

The full text of the studies was retrieved and studies that satisfied our eligibility criteria, such as agenesis of MLI: unilateral or bilateral absence and presence of associated dental anomalies  were included in this review. At the end only 48 full articles have been selected.



Tooth agenesis is often nonsyndromic, but it can also be associated with oral clefts and several other syndromes9. The prevalence of hypodontia is higher in more severe clefting cases, most likely presenting with the agenesis of a maxillary lateral incisor (in either dentition)9.

Other conditions that have hypodontia as one of their features include Down’s Syndrome and ectodermal dysplasia. Down syndrome is characterized by a combination of phenotypic features that includes typical dysmorphic features, mental retardation, congenital malformations of the heart and gastrointestinal tract are common. Congenital absence of teeth has been reported in 23 to 47%. Lateral maxillary incisors, lower incisors, second premolars, and third molars are the most commonly missing. One or both primary upper lateral incisors are missing in more than 10% of the patients, and peg-shaped maxillary lateral incisors are seen in 10%9.

Dental agenesis is also found in other pathologies like some endocrinopathies (hypopituitarism, hypothyroidism) syphilis, rubella, cleaved palate, radiating deficits of feeding (rickets) or therapies in the first months of pregnancy10. In these syndromes, there is a characteristic pattern of agenesis that is usually different from the overall population11.

 The maxillary lateral incisor is the second most frequently missing tooth after the mandibular second premolar4, even though Muller et al. Found that maxillary lateral incisors experience the most genesis (not including third molar12. It is known that tooth agenesis, especially agenesis of maxillary lateral incisor, contributes to abnormal occlusion and is often associated with various anomalies in other teeth11.

Commonly reduction in the mesiodistal dimensions of tooth crowns has been reported in individuals with hypodontia13.

Tooth-number reduction was associated with crown-size reduction, so that the more teeth were missing the greater the possibility of clinically apparent microdontia in the same individual and the more reduction measured in remaining tooth crowns. A relationship between tooth agenesis and molar crown morphology has also been demonstrated13,14.

 Brook proposed that microdontia and hypodontia are linked genetically as a continuum of tooth size, where a tooth will fail to develop if the tooth germ does not reach a particular tooth size and tooth number “thresholds”14. However, agenesis of maxillary lateral incisors and associated dental anomalies were limited in the literature. Most of the papers published about maxillary lateral incisors agenesis investigated reduced crown size or peg shaped form of the contralateral maxillary lateral incisors among the subjects with unilateral absence of this tooth15.

 Woolf presented data on anomalies associated with agenesis of the maxillary lateral incisor, such as peg laterals . Woolf studied 103 participants who had either unilateral or bilateral agenesis of the maxillary lateral incisor, and the relatives of this test group acting as controls. Results showed that 17.7% of parents and brothers of the sample population also had agenesis of the maxillary lateral incisor or peg- shaped laterals, compared to only 2.8% in the control group. 24 of the 103 participants who had agenesis of the maxillary lateral incisor also had a peg-shaped lateral incisor. Members of the same family tended to show the same location and pattern of agenesis. Evidence of a genetic association was demonstrated in this population16.

 Subsequently Garib et al. observed that in the 80.3% of the sub-sample of patients with unilateral upper agenesis of the upper incisor had microdontia of the contralateral incisor17.

 In a study published in 1998, Baccetti showed significant reciprocal associations between agenesis of second premolars and reduced upper lateral incisors. The group with agenesis of second premolars showed a higher prevalence (18%) of small maxillary lateral incisors than did the control group. and, conversely, the group with small maxillary laterals showed a higher prevalence (42%) of aplasia of second premolars than did their control group18. In the same study Baccetti reported  palatal canine displacement showed significant reciprocal associations with small size of maxillary lateral incisors and absence of second premolars in a study of a population with no orthodontia18.

 In a study by Garib et al. (2009) in 203 patients with unilateral or bilateral agenesis of the lower second premolar, 8.1% of the sample exhibited concomitant palatal impacted upper canine, five times higher than the general population19.

Becker et al. (1981) and Brin et al. (1986) reported that displaced canines and missing or peg-shaped upper lateral incisors appeared simultaneously9. Zilberman et al. (1990) in a study of orthodontic patients with at least one palatal canine showed that, in a high percentage of cases, the lateral incisors adjacent to these canines were  missing20. In this study, 46% of the probands with palatal canines had an anomalous lateral incisor; 5% of the parents and 11% of the siblings also had palatal canines and anomalous lateral incisors, in 31% and 28%, respectively19.

 Another common feature of dental agenesis is the ectopic positioning of the permanent teeth. This is likely caused by the absence of neighbouring teeth available to guide them during eruption or by the lack of space for them to erupt into. Transposition of teeth is also seen more commonly in individuals with dental agenesis21.

As far as the ectopic eruption of the second lower premolar in the distal direction is concerned, Garib et al., In a study of 126 patients, found that 4% of subjects with agenesis of the lateral area had a lowering of the second lower premolar but inclusion was thought to be a rare occurrence16.

 Ectopic permanent canines were shown to associate with hypodontia in another Finnish study. The frequency of hypodontia was analyzed in 106 patients treated for ectopic canines and their family members: 36% of the patients and 20% of the first-degree relatives were missing some permanent teeth22.

Peck et al. (1996, 1998) reported significantly elevated hypodontia frequencies in individuals with either maxillary canine-first premolar transposition, palatal displacement of the maxillary canine, or mandibular lateral incisor-canine transposition23,24.

 The prevalence of tooth rotation, together with agenesis of nonadjacent teeth, was studied by Baccetti (1998) in a sample of 1620 subjects and in a control group of 1000 individuals. The occurrence of tooth rotation in association with agenesis of nonadjacent teeth was significantly higher than in the control group for all the categories of tooth rotation. This study concluded that rotation of premolars is significantly associated with congenitally missing upper lateral incisors. Significant associations also appeared between unilateral agenesis of upper lateral incisors and rotation of of the lateral incisor on the other side of the dental arch, and between unilateral agenesis of premolars and rotation of premolars on the other side of the arch17.

Pinho et al. investigated other associated developmentally absent teeth and supernumerary teeth.

Although no supernumerary tooth was found, they found that 12.8 % of the subjects with maxillary lateral incisors agenesis had absence of other teeth and most frequently observed missing teeth were maxillary and mandibular premolars25.

 Delays in tooth development are another common fea- ture, whereby the absence of a permanent successor delays the normal resorption of the roots of the primary teeth. Indeed, the deciduous teeth may be retained for up to 40 or 50 years26.

Furthermore, approximately 46% of individuals with tooth agenesis also have short roots of other permanent teeth9.


There are dental abnormalities associated with dental agenesis that should be sought and investigated in patients with agenesis, particularly with agenesis of upper lateral incisors, and especially in young children for whom it is crucial to intercept these anomalies as early as possible by the orthodontist, in order to establish proper therapy.


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[2] Woodworth DA, Sinclair PM, Alexander RG. Bilateral congenital absence of maxillary lateral incisors: a craniofacial and dental cast analysis. Am J Orthod. 1985;87:280–93.

[3] Stamatiou J, Symons AL. Agenesis of the permanent lateral incisor: distribution, number and sites. J Clin Pediatr Dent. 1991;15:244–6. 

[4] Polder B.J., Van't Hof M.A., Van der Linden F.P., Kuijpers-Jagtman A.M. A meta-analysis of the prevalence of dental agenesis of permanent teeth. Community Dent Oral Epidemiol. 2004 Jun;32(3):217-26.

[5]Altug-Atac A.T., Erdem D. Prevalence and distribution of dental anomalies in orthodontic patients. Am J Orthod Dentofacial Orthop. 2007 Apr;131(4):510-4.

[6] Pini N.I., Marchi L.M., Pascotto R.C. Congenitally missing maxillary lateral incisors: update on the functional and esthetic parameters of patients treated with implants or space closure and teeth recontouring. Open Dent J. 2015 Jan 6;8:289-94.

[7] Gomes RR, da Fonseca JA, Paula LM, Faber J, Acevedo AC. Prevalence of hypodontia in orthodontic patients in Brasilia, Brazil. Eur J Orthod. 2010;32:302–6

[8] Zhu JF, Marcushamer M, King DL, Henry RJ. Supernumerary and congenitally absent teeth: a literature review. J Clin Pediatr Dent. 1996;20:87–95.

[9] Arte S., Phenotypic and genotypic features of familial hypodonita. Academic Dissertation, University of Helsinki, Helsinki, Finland, 2001.

[10]Nordgarden H., Jensen J.L., Storhaug K. Oligodontia is associated with extra-oral ectodermal symptoms and low whole salivary flow rates. Oral Dis. 2001 Jul;7(4):226-32.

[11] Nieminen P. Genetic basis of tooth agenesis. J Exp Zool B Mol Dev Evol. 2009 Jun 15;312B(4):320-42.

[12] Muller TP, Hill IN, Peterson AC, Blayney JR. A survey of congenitally missing permanent teeth. J Am Dent Assoc 1970;81:101-7.

[13] Garn S.M., Lewis A.B.The gradient and the pattern of crown-size reduction in simple hypodontia. Angle Orthod. 1970 Jan;40(1):51-8.

[14] A. H. Brook, “A unifying aetiological explanation for anomalies of human tooth number and size,” Archives of Oral Biology, vol. 29, no. 5, pp. 373–378, 1984.

[15] Celikoglu M., Kamak H., Yildirim H., Ceylan I. Investigation of the maxillary lateral incisor agenesis and associated dental anomalies in an orthodontic patient population. Med Oral Patol Oral Cir Bucal. 2012 Nov 1;17(6):e1068-73.

[16] Woolf C.M. Missing maxillary lateral incisors: a genetic study. Am J Hum Genet. 1971 May;23(3):289-96.

[17] Garib D.G, Alencar B.M., Lauris J.R., Baccetti T. Agenesis of maxillary lateral incisors and associated dental anomalies. Am J Orthod Dentofacial Orthop. 2010 Jun;137(6):732.

[18] Baccetti T. A controlled study of associated dental anomalies. Angle Orthod. 1998 Jun;68(3):267-74.

[19] Garib D.G., Peck S., Gomes S.C. Increased occurrence of dental anomalies associated with second-premolar agenesis. Angle Orthod. 2009 May;79(3):436-41.

[20] Zilberman Y., Cohen B., Becker A. Familial trends in palatal canines, anomalous lateral incisors, and related phenomena. Eur J Orthod. 1990 May;12(2):135-9.

[21]Peck S., Peck L., Kataja M. Concomitant occurrence of canine malposition and tooth agenesis: evidence of orofacial genetic fields. Am J Orthod Dentofacial Orthop 2002;122:657-60.

[22] Pirinen S., Arte S., Apajalahti S.Palatal displacement of canine is genetic and related to congenital absence of teeth. J Dent Res. 1996 Oct;75(10):1742-6.

[23] Peck S., Peck L., Kataja M.Prevalence of tooth agenesis and peg-shaped maxillary lateral incisor associated with palatally displaced canine (PDC) anomaly. Am J Orthod Dentofacial Orthop. 1996 Oct;110(4):441-3.

[24] Peck S., Peck L., Kataja M.Mandibular lateral incisor-canine transposition, concomitant dental anomalies, and genetic control. Angle Orthod. 1998 Oct;68(5):455-66.

[25] Pinho T, Tavares P, Maciel P, Pollmann C. Developmental absence of maxillary lateral incisors in the Portuguese population. Eur J Or- thod. 2005;27:443-9.

[26]Haselden K., Hobkirk J.A., Goodman J.R., Jones S.P., Hemmings K.W. Root resorption in retained deciduous canine and molar teeth without permanent successors in patients with severe hypodontia. Int J Paediatr Dent. 2001 May;11(3):171-8.

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